ETHYL ALCOHOL, FROM WOOD WASTE. 23 



show that the first two are not the same as ^-glucose in reducing 

 power. Browne says: 



The statement has been made that in a mixture of sugars the reducing power of the 

 individual sugars is somewhat modified by the other members present. The writer 

 has subjected this statement to a thorough test and can discover no such influence. 



However, no wide ranges of varying sugar concentrations were 

 tried by Browne, and therefore this point was checked up at the Forest 

 Products Laboratory with mixtures of arabinose, xylose, and ^-glu- 

 cose, and no modifying influence in mixtures was found at widely vary- 

 ing concentrations. Since there is no mutual influence, it is possible 

 to correct the analyses after fermentation, if desired, for the non- 

 fermentable sugars may in most cases be regarded as pentoses such 

 as xylose. As the ratio of the reduction factors of xylose and dex- 

 trose, as found by Browne and corroborated by the work at the 

 Forest Products Laboratory, was 0.983, no great error has been 

 introduced, because the reducing power of xylose is so nearly that 

 of dextrose. 



The main error due to sampling, other than unavoidable ones aris- 

 ing from the sampling of large quantities of material, has been found 

 and in a great measure overcome. On the sugar and alcohol yield 

 sheets it will be noticed that up to cook 43 it was necessary to discard 

 one or more of the fermentations in many of the cooks, because of 

 poor yields or abnormal fermentation efficiencies. The reasons for 

 these discrepancies were apparent. After the sugar was extracted 

 from the wood and the acid solution had been neutralized, the clari- 

 fied, settled neutral juice was concentrated to a heavy sirup in vacuo 

 and stored as such. In the different cooks, varying amounts of 

 sludge were precipitated when the neutral juice was concentrated. 

 This sludge consists mainly of calicum sulphate, some calcium acetate, 

 and calcium formate, with possibly some crystallized sugar. When a 

 fermentation was to be made, the heavy sirup was diluted with water 

 to give a solution of about 12.5° Brix. Previous to cook No. 43, 

 samples of the 12.5° Brix juice were taken for analysis along with the 

 sludge remaining in the carboy before sterilization. After that time 

 the samples were made up and allowed to stand all night; the clear 

 juice was then siphoned out into a clean 5-gallon bottle and given two 

 intermittent sterilizations. The sample for analysis and the final 

 Brix reading were taken at the same time that the 240 c. c. sample 

 was taken for making up the sprout mash. This apparently obviated 

 all of the former difficulties, and but few fermentations were dis- 

 carded after this scheme was inaugurated. In addition, the sugar 

 data in each run were much more concordant. 



